The present disclosure relates to containers for dispensing liquids, particularly refill containers for dispensing inks or solvents for use in printers, such as ink jet printers, particularly continuous ink jet printers.
In ink jet printing systems the print is made up individual droplets of ink generated at a nozzle and propelled towards a substrate. There are two principal systems: drop on demand where ink droplets for printing are generated as and when required; and continuous ink jet printing in which droplets are continuously produced and only selected ones are directed towards the substrate, the others being recirculated to an ink supply.
Continuous ink jet printers supply pressurized ink to a print head drop generator where a continuous stream of ink emanating from a nozzle is broken up into individual regular drops by an oscillating piezoelectric element. The drops are directed past a charge electrode where they are selectively and separately given a predetermined charge before passing through a transverse electric field provided across a pair of deflection plates. Each charged drop is deflected by the field by an amount that is dependent on its charge magnitude before impinging on the substrate whereas the uncharged drops proceed without deflection and are collected at a gutter from where they are recirculated to the ink supply for reuse. The charged drops bypass the gutter and hit the substrate at a position determined by the charge on the drop and the position of the substrate relative to the print head.
Typically the substrate is moved relative to the print head in one direction and the drops are deflected in a direction generally perpendicular thereto, although the deflection plates may be oriented at an inclination to the perpendicular to compensate for the speed of the substrate (the movement of the substrate relative to the print head between drops arriving means that a line of drops would otherwise not quite extend perpendicularly to the direction of movement of the substrate).
In continuous ink jet printing a character is printed from a matrix comprising a regular array of potential drop positions. Each matrix comprises a plurality of columns (strokes), each being defined by a line comprising a plurality of potential drop positions (e.g. seven) determined by the charge applied to the drops. Thus each usable drop is charged according to its intended position in the stroke. If a particular drop is not to be used then the drop is not charged and it is captured at the gutter for recirculation. This cycle repeats for all strokes in a matrix and then starts again for the next character matrix.
Ink is delivered, under pressure, to the print head by an ink supply system that is generally housed within a sealed compartment of a cabinet that includes a separate compartment for control circuitry and a user interface panel. The system includes a main pump that draws the ink from a reservoir or tank via a filter and delivers it under pressure to the print head. As ink is consumed the reservoir is refilled as necessary from a replaceable ink container that is releasably connected to the reservoir by a supply conduit, with the replacement ink suitably being supplied through an ink top-up pump which is connected to an outlet port of the replaceable ink container by means of the supply conduit. The ink is fed from the reservoir, suitably via a flexible delivery conduit to the print head by the main pump. The unused ink drops captured by the gutter are recirculated to the reservoir via a return conduit by a pump. The flow of ink in each of the conduits is generally controlled by solenoid valves and/or other like components.
As the ink circulates through the system, there is a tendency for it to thicken as a result of solvent evaporation, particularly in relation to the recirculated ink that has been exposed to air in its passage between the nozzle and the gutter. In order to compensate for this “make-up” solvent is added to the ink as required from a replaceable solvent container so as to maintain the ink viscosity within desired limits. This solvent may also be used for flushing components of the print head, such as the nozzle and the gutter, in a cleaning cycle. A solvent top-up pump may be used for supplying the solvent from the replaceable solvent container via a supply conduit.
Hence a typical continuous ink jet printer has both a replaceable ink container and a replaceable solvent container. Suitably, each container has a port through which the respective liquid, ink or solvent, is dispensed. The port for each container is connected, via fluid-tight means, to a pumping system adapted to dispense liquid from the container to the reservoir. In this description, both replaceable ink containers and replaceable solvent containers are referred to as containers or cartridges.